Audio problem: When Gaby goes to introduce Angie to Heidi Klum at the fashion agency, Gaby goes up to Heidi and says "It's me, Gaby." When the camera angle changes to behind Gaby in the next shot, she is saying the same thing again, but no words are coming out.
Audio problem: During the dinner scene at the Scavo's home, Lynette tells Irina that her son Preston is "blinded by a piece of Eurotrash who would sell her own mother for a pair of designer jeans." When the camera changes to behind Lynette in the next shot, she can be saying the words "designer jeans" again, but this time with no sound.
Audio problem: When Gaby sees Paulina Poriskova in the restaurant, she puts out her arms and says, "Give me a hug!" but her lips barely move.
Answer: Kayla was sent away in episode 16 (The Gun Song) in season 4, after falsely accusing Lynette of child abuse. She now lives with her grandparents - probably Nora's parents.
I'm curious why we never see her again, why she never talked about, and why Tom never mentions visiting her.